JPS6216515A - Monitoring device for plasma treating device - Google Patents

Abstract

PURPOSE:To enable detecting and monitoring operations with sufficient sensitivity by to be performed a method wherein the fine grains located in a plasma treating device are monitors using the monitoring device having a laser- introducing means, a detector with which a laser beam is detected and a gate sampler. CONSTITUTION:A photo detector 7 is connected to a gate sampler 8, and the signal sent from the photo detector 7 is gate-sampled by the gate sampler 8 in synchronization with a pulse-like laser beam and in line with the time duration of the laser beam. To be more precise, the pulse-like laser A, which passed through a plasma processing device 1 and advanced straight without receiving the scattering by the fine grains, is received by the light-receiving device 9 provided outside the plasma processing device 1, and the gate signal B corresponding to the time duration of the received pulse-like laser beam is fed to the gate sampler 8 by the light-receiving device 9. The signal C sent from the photo detector 7 is gate-sampled by the gate sampler 8 in accordance with said gate signal. The output signal obtained by the gate sampler 8 is normally recorded in a recording device.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a device for detecting and monitoring particulates in a plasma device used in the film forming process of semiconductor devices.

Conventional technology In plasma equipment used in the film forming process of semiconductor devices, fine particles are generated within the plasma equipment during the film forming process, and these fine particles adhere to the surface of the substrate being processed and have an adverse effect on the substrate. Therefore, it is necessary to monitor particulates in the plasma device.

In other words, if the plasma density is increased by using higher RF power in order to increase the deposition rate, the number of particles formed by molecules heading towards the substrate to be deposited colliding with each other before reaching the substrate will be reduced. and these fine particles will adhere to the substrate. Since the number of fine particles formed depends primarily on the plasma density, by measuring the number of fine particles it is possible to control the plasma state within the plasma device.

By the way, conventional methods for measuring fine particles in the gas phase include microscopy, gravity sedimentation, centrifugal sedimentation, inertial method, electric mobility method, diffusion method, condensation nucleus method, and light scattering method. In the film forming process, etc., a method is generally used in which a laser that oscillates continuously over time, such as an Hc-Na laser, is used as a light source and scattering by fine particles is detected.

When this method is applied to detecting and monitoring particulates in a plasma device, it is impossible to sensitively detect the laser beam scattered by the particulates due to strong light emission from the plasma itself.

Problems to be Solved by the Invention As described above, the method of detecting scattering by particles using a laser beam that oscillates continuously in time, such as a He-Ne laser, is not suitable for detecting and monitoring particles in a plasma device. When applied, there is a problem that particles within the plasma device cannot be detected with sufficient resolution due to the light emission of the plasma.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a monitoring device for a plasma device that improves the conventional method of detecting particles using a laser beam and is capable of detecting and monitoring particles in the plasma device with sufficient sensitivity.

Means for Solving the Problems In order to achieve the above object, the monitoring device for a plasma device according to the present invention includes a laser introducing means for introducing a pulsed laser beam into the plasma device, and a laser beam introducing a pulsed laser beam into the plasma device. It has a detector that detects the C1f light scattered by the fine particles, and a sampler that performs lean-one ringing of the signal from the detector in synchronization with the pulsed laser beam, and detects the fine particles in the plasma device. It is characterized by being able to be monitored.

As the laser used in the present invention, a YΔG laser, a nitrogen laser, a pulsed dye laser, etc. can be used.

Function: In the monitoring device for a plasma device of the present invention configured as described above, the laser beam scattered by the particles in the plasma device is synchronized with the pulsed laser beam through the detector and the gate device, and its time width is In addition, it can be detected without being affected by plasma emission within the plasma itself.

The output signal thus detected can be used to monitor and control plasma conditions within the plasma device.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the configuration of a monitoring device for a plasma device according to the present invention, where 1 is a plasma processing device, and 2 is a laser device constituting a laser introduction means. Generates a pulsed laser beam with a duration of less than a second.

This pulsed laser beam enters the plasma processing apparatus @ 1 through a light introduction window (not shown) of the plasma processing apparatus 1 as indicated by an arrow 3 in the drawing.

Similarly, the light exits through a light exit window (not shown).

Reference numeral 4 represents a light beam scattered by fine particles existing in the plasma processing apparatus 1, and this scattered light beam 4 is focused by a condensing lens 5, and then passed through a spectroscope or filter 6.
The light enters the photodetector 7 via.

The condenser lens 5, the spectrometer or filter 6 and the photodetector 7 are arranged at a predetermined angle to the axis of the introduced laser beam 3 so as to receive the desired scattered beam. The photodetector 7 is connected to a gate sampler 8, which gate-samples the signal from the photodetector i1!87 in synchronization with the pulsed -11 light beam in accordance with its time width. In other words, plasma process equipment @
The pulsed laser beam ((a) in FIG. 2) that has passed straight through the interior of the plasma processing apparatus 1 without being scattered by particles is received by the light receiving device 9 provided outside the plasma processing apparatus 1. 9 supplies the gate sampler 8 with a gate signal (FIG. 2 (b)) corresponding to the time width of the received pulsed laser beam. Thereby, the gate sampler 8 gate-samples the signal from the photodetector 7 ((c) in FIG. 2) according to this gate signal. Gate sampler 8
The output signal obtained by can typically be recorded on a recording device (not shown). Note that 10 is a power supply device 12 of the plasma processing apparatus 1.

Effects of the Invention As explained above, the monitoring device for a plasma device according to the present invention includes a laser introducing means for introducing a laser beam that oscillates in a pulsed manner into the plasma device, and a laser beam that is scattered by fine particles in the plasma device. Since the device is equipped with a detector that detects the pulsed laser beam and a non-branch that samples the signal from the detector in synchronization with the pulsed laser beam, the sampling time is very short and the steady It is possible to detect fine particles with high sensitivity without being affected by the plasma emission that is continuously emitted.This allows the plasma power, sample gas pressure, flow rate, etc. to be adjusted to create plasma conditions that do not generate fine particles. It can be easily set, and as a result, high quality film formation can be performed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a monitoring device for plasma equipment according to the present invention, and FIG. 2 is a waveform diagram showing a laser beam, an output signal of a photodetector, and a gate signal. In the figure, 1: plasma process device, 2: laser introduction means, 4: scattered light, 7: photodetector, 8: Nige-1-Dokunanpura, 9: light receiving device. Figure 1 Figure 2 (b)

Claims (1)

[Claims] a laser introducing means for introducing a pulsed laser beam into the plasma device; a detector for detecting the laser beam scattered by particles in the plasma device; and a detector for detecting the laser beam in synchronization with the pulsed laser beam. 1. A monitoring device for a plasma device, comprising a gate sampler for sampling a signal from the plasma device, and is capable of monitoring particulates in the plasma device based on an output signal of the gate sampler.